隨著過去數十年科技設備的使用日益地增長，原本使用的傳統射頻波段開始無法滿足過多設備的需求，所以研究人員開始在頻譜上尋求其他頻段，其中一個頻段為可見光，將可見光作為傳輸訊息的優點在於頻段比射頻頻段高出1300倍，而且也比射頻具備較佳的安全性。然而，因為可見光無法穿透牆壁跟不透明障礙物的物理特性，使得可見光仍具有不可忽視的缺點，而且相對於射頻網路(RF)，可見光網路(VLC)的覆蓋範圍較小。於是研究人員提出合併射頻網路和可見光網路技術，作為室內無線通訊的一種新穎的方法，稱之為異質性無線網路。此無線網路不僅可以同時擁有可見光網路和射頻網路的優點，亦可以彌補彼此的缺點，而且能夠同時使用兩塊不重疊的頻譜，增加整體網路的效能。其中一種異質性無線網路是利用協作式非正交多重存取技術實現，相較於非正交多重技術的異質性網路，此網路可以降低整體系統頻寬中斷機率。
利用協作式非正交多重存取技術之異質性無線網路需要討論，例如無限存取點的資源配置問題、選擇適當的中繼者、中繼者資源配置和中繼者資源重新配置問題。對於目前大多數文獻只使用基於通道增益為出發點所提出的資源配置方法，這些方法缺乏考慮使用者的需求，導致無法有效分配資源，無法更好的降低系統頻寬中斷機率。本論文提出基於考慮使用者需求與通道增益的資源配置方法，而且選擇適當中繼者的幫助，讓每個使用者可以不耗費過多不需要的時間之餘，降低整體系統頻寬中斷可能性的發生。最後，模擬結果顯示我們提出的方法在系統頻寬中斷機率和花費時間間隔數都有所改善，而且也降低使用的中繼者數量。

With the increasing use of technology devices over the past decades, the traditional radio frequency (RF) spectrum has become insufficient to meet the growing demand of numerous devices. As a result, researchers started exploring alternative frequency spectrum, and one such spectrum is visible light. Utilizing visible light for communication offers several advantages over RF, including the spectrum that is 1300 times larger and better security. However, the physical characteristics of visible light, such as its inability to penetrate walls and opaque obstacles, impose inherent limitations on its usability. Compared to RF networks, visible light communication (VLC) has a smaller coverage range. To overcome these limitations, researchers have proposed the integration of RF and VLC technologies, forming a novel approach for indoor wireless communication known as heterogeneous wireless networks. These networks can leverage the advantages of both VLC and RF networks while compensating for their respective drawbacks. Moreover, they can utilize two non-overlapping spectra simultaneously. One type of heterogeneous wireless network that achieves this is based on cooperative non-orthogonal multiple access (CoNOMA) techniques. Compared to hybrid networks based on orthogonal multiple access techniques, this network enhances the probability of users receiving correct messages, thereby reducing the probability of bandwidth outage in the overall system.
The heterogeneous wireless network utilizing CoNOMA technique requires further investigation, such as access point resource allocation, the appropriate relay selection, relay resource allocation and relay resource reallocation. Most existing research focus on resource allocation methods based only on channel gains, without considering the users' requirements. As a result, these methods fail to efficiently allocate resources. In this paper, we propose a resource allocation method that considers both user demand and channel gain. We also select suitable relays to assist users, ensuring that each user reduces the probability of not receiving messages without redundant unnecessary time, and reduces the possibility of bandwidth outage in the overall system. Finally, the simulation results show that our proposed method has improved the system bandwidth outage probability and the time slots of consumption. Moreover, it has also reduced the number of relays used.

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